The United States will shift a majority of its warships to the Asia-Pacific region by 2020, Defense Secretary Leon Panetta said Saturday, giving the first details of a new US military strategy. Fleshing out details of a strategic pivot to Asia announced in January, Panetta said the United States would reposition its Navy fleet so 60 percent of its battleships would be assigned there, up from about 50 percent now, while maintaining six aircraft carriers in the region. The US defense secretary, speaking at an annual security forum in Singapore, also sought to dispel the notion that the shift, after more than a decade of war in Afghanistan and Iraq, was designed to contain China's emergence as a global power. He acknowledged differences between the world's two largest economies on a range of issues, including the South China Sea. “We're not naive about the relationship and neither is China,” Panetta told the Shangri-La Dialogue attended by senior civilian and military leaders from about 30 Asia-Pacific nations. “We also both understand that there really is no other alternative but for both of us to engage and to improve our communications and to improve our (military-to-military) relationships,” he said. “That's the kind of mature relationship that we ultimately have to have with China.” Some Chinese officials have been critical of the US shift of military emphasis to Asia, seeing it as an attempt to fence in the country and frustrate Beijing's territorial claims. China has downgraded its representation to the Shangri-La Dialogue from last year, when Defense Minister Liang Guanglie attended and met then-US Defense Secretary Robert Gates. This year the Chinese military was represented by the vice president of the Academy of Military Sciences. Panetta, by contrast, was accompanied by General Martin Dempsey, the military's top officer as chairman of the Joint Chiefs of Staff, and Admiral Samuel Locklear, the head of the US Pacific Command. The US Defense Secretary was at the start of a seven-day visit to the region to explain to allies and partners the practical meaning of the US military strategy unveiled in January that calls for rebalancing American forces to focus on the Pacific.